Long-term companies in the south bay that have no (or virtually no) SF tech presence. Just off the top of my head: Google/Alphabet, Facebook, Oracle, Texas Instruments, National Semiconductor, Intel, AMD, Applied Materials, Apple, Yahoo, Tesla, Palantir, and so on and so on.

Yes there are lots of kids in SF trying to get their website turned into the next unicorn. That does not make SF the "center of the tech world", it makes it the "center of the SF tech startup world".